The cold chain is the main mode for storage and transportation of Tan sheep meat,while quality issues caused by cold chain storage have received extensive attention.Lipid molecules are diverse and easily affected by the external environment,which are one of the main nutrients determining the meat quality of Tan sheep.In this study,a method was developed for the determination of lipid variations and molecular fragmentation mechanism by ultra high performance liquid chromatography-quadrupole-orbitrap mass spectrometry(UHPLC-Q-Orbitrap MS/MS) combined with lipidomics.The samples were extracted with isopropanol,and analyzed by mass spectrometry in full scan mode and secondary scan mode.A total of 48 significantly changed lipids were identified,including 8 fatty acyl carnitines,23 phosphatidylcholines(PC),3 lysophosphatidylcholines(LPC),13 phosphatidylethanolamines(PE) and 1 lysophosphatidylethanolamine(LPE).The changes showed the transient up regulation trend of partial PC,PE and fatty acyl carnitine in first 12 days,followed by down regulation of PC,PE and fatty acyl carnitine,as well as the up regulation of LPE and LPC in whole cold chain storage.The transient accumulation of PC,PE and fatty acyl carnitine could cause a large number of oxidation reactions after 12 days,which further indicated that the optimum cold chain time was 12 days.This method was suitable for the separation and quantitation of lipid molecules in complex matrix,which provided a basis for lipid variations and quality control of meat and meat products during cold chain storage.